Wear bushing structure for percussive tools



Aug. 26, 1952 J. c. CURTIS Erm.' 2,608,181

WEAR RUSHING STRUCTURE RoR PERcUssIvE TooLs Filed Aug. 141947 Patented ig. 26,

WEAR BUSHING STRUCTURE FOR PERCUSSIVE TOOLS John C. Curtis and Elmer G. Gartin, Claremont,

N. H., assignors to Joy Manufacturing Company, a corporation of Pennsylvania Application August 14, 1947, Serial No. 768,546

(c1. 121-s2i 12 Claims.

`This .invention relates to liuid operated tools and more particularly to improvements in the wear bushing structure of a percussive tool, such as a hammer rock drill.

In fluid operated tools, such as hammer rock drills, considerable wear occurs between the piston striking bar and the front buier ring and between the cylinder and the rotating chuck sleeve of the drill chuck mechanism. In known constructions, a wear bushing has been inserted in the bore of the front buffer ring to reduce wear, but considerable diiculty has been encountered in holding this bushing in place while still enabling ready replacement thereof when desired. The present invention contemplates improvements over such known constructions in that an improved wear bushing arrangement isV provided for the front buffer ring and the cylinder,.substantially to reduce wear. The bushing structure of the present invention embodies a wear bushing inserted in the bore of the front buffer ring and a cylinder wear bushing forthe rotatable chuck sleeve wherein the cylinder bushing is so arranged and so coacts with the buffer ring ,bushing as to lock the latter in place. Upon disassembly of the rock drill, the buiier ring bushing maybe readily replaced, and, conversely, the parts may be readily assembled. rInhe structure is simple in design and relatively rugged, well adapted to meet the demands of service.

An object of the present invention is to provide an improved wear bushing structure for a fluid operatedtool.t Another object is to provide an improved wear bushing arrangement for the front buffer ring and cylinder of a hammer rock drill whereby wear of relatively costly parts is substantially reduced. A further object is to provide an improved wear bushing structure wherein one bushing is so arranged and so coacts with the other bushing to lock the latter in its operative position. Yet another object is to provide an improved wear bushing arrangement whereby the piston striking bar and rotatable chuck sleeve are supported and guided in an improved manner.- Other objects andadvantages ofthe invention'will, however, hereinafter more yfully appear.

In the accompanying drawing there is shown for purposes of illustration one form which the invention may assume in practice.

2 In this drawing: Fig. 1 is a, view in central longitudinal section through a hammer rock drill in which an illustrative form of the invention is embodied. Fig. 2 is a perspective view, partially in section, illustrating the frontrcylinder bushing.

Fig. 3 is a perspective view of the bufferrin Y tting the cylinder bore and an elongated re-,.

duced cylindrical front extension or striking bar 5 for delivering impact blows to the shank 6 of a working implement l, herein a conventional lugged rock drill steel. Suitably attached to the front end of the motor cylinder is a chuck housing 8 having a bore 9 in which a chuck sleeve I0 is rotatably mounted, and carried within and rotatable with this chuck sleeve is a chuck bush-l ing II for receiving and supporting the lugged shank 6 of the drill steel. Suitably coupled at I2, as by interlocking jaws, to the front end of and rotatable with the chuck sleeve I0 is a driver member I3 within which the steel shank is suitably locked and provided with usual drive lugs engaging the lugs of the steel shank for rotating the steel with the chuck sleeve, all in a conventional manner. The driver member I3 is 1rotatably mounted in a sleevelike wear bushing I4 supported within the forward portion of the chuck housing bore. Secured within a bore I5' aligned with the cylinder bore 2 is a front'buifer ring or fron-t cylinder head I6, while arranged in a rearwardly located bore I1,. likewise aligned with the cylinder bore, is a rear cylinder head or rear head plate I8. A conventional automatic uid distributing valve mechanism I9, arranged rearwardly of and associated with the rear head plate, serves to control the ilow of motive uid from a suitable supply connection 20 to the opposite ends of the cylinder bore 2 for eecting reciprocation of the hammer piston. A spirally,

grooved rie bar 2l is suitably slidably internected to a ratchet and pawl device 22 which serves to hold the rifle bar against rotation in one direction while permitting free bar rotation in the opposite direction. As the hammer piston moves rearwardly, the rifle bar is held against rotation by the ratchet and pawl device, thereby -toeffect rotation of the piston, and as the piston moves forwardly, the ratchet and pawl device slips to permit free rotation of the rie bar, thereby enabling the piston bar to strike an unimpeded blow against the piston shank. Rotation of the piston is transmitted to the drill steel through straight grooves 23 on the piston striking bar 5 slidingly interlocked with straight lugs on a chuck nut 24 fixed to the chuck sleeve l0. Thus, as the hammer piston reciprocates to actuate percussively the drill steel, the latter is intermittently rotated, likewise all in a conventional manner.

As is usual in hammer rock drills of the type disclosed, encircling the front buffer ring I6 is an annular lubricant vreservoi; 25 provided with a suitable filler plug 26 (Fig. 4) and containing a suitable lubricant. Passage means 21 conductsuid under pressure from the fiuid supply connection 20 to the lubricant reservoir, and passage means 28 conducts lubricant from the reservoir to therotating chuck parts in a well known manner. When the pressure in the passage means 28 is reduced, the pressure in the reservoir, acting on Ythe lubricant therein, forcessome lubricant from the reservoir and through the passageY means 28 to the parts to be lubricated, in a well known manner.

Now referring to thel improved wear bushing, structure, it will be observed that .fitted in a bore 29v inthe. front buffer ring or front head I64 is, awear bushing 30, (Fig. 3) in, which the piston striking bar or front piston extension is slidably.

guided. This bushing is of sleevelike form andl engages, at its rear end, a forwardly facing shoul.-

der.- 3lon, the buffer ring. Arranged in a front.

bore 32` in the cylinder. is. a. wear bushing. 33 (Fig. 2). having an. inwardly`A directed circular. flange surrounding thelcircular front reduced end 3.5 of the Awear bushing 30, as shown in Fig. 1'. Therear-surface of thevflange 3Lengages aforwardly facing shoulder 36 on the bushing 30 forv lockinglv the latter in4 place within the bore of thebuierring. The rear endof the chucksleeve ls.journaled.in the bushingk 33- in the manner: shown. Thus. the wear bushing. 30. reduceswear of-the buffer ring while the bushing 33reduces wear of the cylinder, andthe bushingsv are so arranged and constructedand so coact with one another thatthe cylinder bushing. 33.-locks the bushing 3l)v in place.

When the lfront chuck housing 8 is suitablyv detached from thercylinder, it may be removed, together with the chuck partslcontained therein, forwardly from the cylinder, and during such forwardmovement, the.lugs ofthe chucknui; 24y

slldeforWardly. fromthe straight grooves-23 on thepiston striking bar in an obvious manner. The cylinder bushing 33 remains -in the position shown in Fig. Lupon removal of thevfron-t chuck structure. Thevvback head structure, includingv therrear head plate and distributing valve mechanism, maythen be suitably detached from the rear cylinder. The front buffer ring has a tight press t within the cylinder bore l5, and whenY the rear headstructure is detached, the buffer ring', together withA the wear bushing-30, may 'beA forcedrearwardly--fromthe bore ;'and uponV removal of the buffer ring,- the wear bushingmay be readily replaced when worn. In the event the cylinder bushing 33 becomes worn, it may at that time also be readily replaced. The front chuck structure and the rear head structure may then be reassembled with respect to the cylinder, again bringing the bushings 30 and 33 together as shown in Fig, 1, with the front cylinder bushing locking the buffer ring bushing in place.

As a result of this invention, it will be noted that an improved wear bushing structure is provided whereby wear of relatively costly parts necessitating replacement thereof issubstantially reduced. By arranging the bushings in the novel manner disclosed, with the front cylinder bush- .ing coacting with the buffer ring bushing, the

latter is firmly locked in place within the front buffer ring. Due to the improved bushing arrangement disclosed, the bushings may be readily replaced when worn upon disassembly of the drill. Other advantages of the invention will be clearly apparent to those skilled in the art.

While there is in this application specifically described one form which the invention may assume in practice, it will be understood that this form of the same is shown for purposes of illustrationand that the invention: may be modified and embodied in variousother forms without depart-Y ing, from its spirit or the scope of the appended claims.

What we claim as. new' and desire'to secure by Letters Patent is:

1. In a. percussive. tool comprisingy a cylinder having'a bore, a piston reciprocable insaid-bore and having a reduced forward:extension,.a front buffer ring, a chuck housingsecured'to said cyl'- inder and a rotatable chuck sleeve mounted: in'y said chuck housingy and projecting rearwardly into said cylinder, the improvement consisting of a replaceable wear. bushing fitted.' insaidfront buffer ring for guiding said piston .extension and'. removable axially forwardlylfromsaid ring, andxa= replaceable cylinder wearibushing' in which the= rearward portion of saidchuck. sleeve is receivedand rotatably mounted,4 saidA cylinder bushing; arranged coaxialwith said: buier. ring bushing.. at the forward side of the latter and coacting with said buffer ring bushinglto hold the latteragainst forward axial displacement'l from said' buler ring.

2. In a percussive tool comprisingaucylinder having a bore, a piston reciprocable in saidboreI and having a reduced forward extension,- a front. bufferrng, a-chuck housingsecured'to said cyl-` inder and arotatablechuck sleevemounteddnr said chuck housing and projecting rearwardlyy into said cylinder, the improvement-consisting of a replaceablev wear bushing ttedinf-saidfront buffer ring for guidingsaid piston extension and' removable axially forwardly-from said ring; saidv buffer ring bushing havingv a'reducedforwardcylindrical portion providing a -forwardly Afacingl shoulder, and a replaceable cylinder wear-bushingin which theV rearward portion of" said -chuckf sleeve is received and rotatably-mounted.'- said' cylinder wear bushing arranged coaxial with'said buffer ring bushingat the forward sideoffthhef latter and havingany inwardly directed rear annu-l lar -flange surrounding said reduced forward por-- tion of saidbuier ring bush-ing. and the-rear'sur" face ofsaid flange abuttingsaid shoulder-tov hold said buffer ring bushing agalnstforwai-d axiai displacement from said buffer ring.

3. In a, uid operatedv tool comprising-a cylinder having abore, a piston-reciprocable in'saidl bore? a front buffer ring," au chuck housing secured"`to' the front end of said cylinder and a rotatable chuck part mounted in said. chuck housing and projecting rearwardly into said cylinder, the improvement consisting of a replaceable sleevelike wear bushing tted in said buffer. ringl for` slidingly guiding said piston and a replaceable cylinder wear bushing in which the rearward portion of said chuck part is received and rotatably mounted, said cylinder wear bushing arranged coaxial with said buffer ring bushing and having a portion coacting with said buier ring bushing for locking the latter against forward axial displacement from said buffer ring.

4. In a uid operated tool comprising a motor having relatively reciprocable motor parts and a rotatable tool chuck, the improvement consisting of a replaceable wear bushing arranged with respect to one motor part in a position to guide the reciprocable motor part, and a replaceable wear bushing positioned with respect to said one motor part rotatably to receive and support said rotatable chuck part, said bushings arranged in coaxial relation and having coacting portions so that one bushing serves to lock the other against axial displacement.

5. In a fluid operated tool comprising a motor having relatively movable motor parts and a chuck mechanism including a rotatable chuck part, the improvement consisting of separate replaceable wear bushings for guiding the reciprov cable one of said motor parts and said rotatable chuck part respectively, said chuck part being received and mounted in its bushing, said bushings arranged in coaxial relation and having coacting Y portions so that one bushing serves to hold the other against axial displacement.

6. In a iiuid operated tool comprising a motor having relatively movable motor parts and a chuck mechanism including a rotatable chuck part, the improvement consisting of separate replaceable wear bushings for guiding the movable one of said motor parts and said rotatable chuck part respectively, Said chuck part being received and mounted in its bushing, said bushings arranged in coaxial relation and having coacting portions one abutting the other so that one bushing serves to hold the other against axial displacement.

'7. In a fluid operated tool, the combination comprising relatively movable parts, one of which is reciprocable and the other rotatable, and a supporting and wear bushing structure comprising a support having a replaceable sleevelike wear bushing supported axially therein for guiding the reciprocable part, and a support having a coacting replaceable front wear bushing axially supported therein and in which the rotatable part is received and rotatably mounted, said sleevelike `wear bushing having a reduced forward end providing a forwardly facing shoulder, and said coacting front bushing having an inwardly directed circular flange surrounding said reduced forward end with its rear surface abutting Said forwardly facing shoulder for holding said sleevelike bushing against forward axial displacement from its support.

8. In a tool of the character disclosed, the combination with relatively movable tool parts one of which is reciprocable and the other rotatable, of a supporting and wear bushing structure comprlsing a support having a replaceable sleevelike wear bushing axially supported therein for guiding the reciprocable part, and a support having a replaceable annular wear bushing axially supported therein in which the rotatable part is received and rotatably mounted for providing a bearing for the rotatable part, said annular wear bushing abutting said sleeve-like wear bushing to hold the latter against axial displacement from its support.

9. In a fluid operated tool comprising a motor having relatively reciprocablel motor parts 'and a chuck mechanism including a rotatable chuck part, the improvement consisting of separate replaceable wear bushings for guiding the reciprocable one of said motor parts and said rotatable chuck part respectively, said chuck part being received and mounted in its bushing, said bushings arranged in coaxial relation and having coacting portions in abutting relation and said portion of said bushing for said rotatable chuck part serving to hold said other bushing against forward axial displacement.

10. In a tool of the character disclosed, the combination with relatively movable tool parts one reciprocable and the other rotatable, of a wear bushing structure comprising a replaceable sleeve-like wear bushing for guiding the reciprocable motor part and a replaceable annular wear bushing coaxial with said sleeve-like bushing and in which said rotatable tool part is received and mounted for rotation, said annular bushing having a rear annular flange abutting a portion of said sleeve-like bushing to maintain the latter against forward axial displacement.

l1. In a tool of the character disclosed, the combination with relatively movable tool parts one reciprocable and the other rotatable, of a replaceable wear bushing structure comprising a sleeve-like wear bushing for guiding the reciprocable Inotor part and having a reduced forward portion providing a forwardly facing shoulder, and a replaceable annular wear bushing in which said rotatable motor part is received and mounted for rotation, said bushings arranged in coaxial relation and said annular wear bushing having an inwardly directed rear flange surrounding said reduced portion and abutting said shoulder for maintaining said sleeve-like bushing against forward axial displacement.

12. In a percussive tool comprising a cylinder having a bore, a piston reciprocable in said bore and having a reduced cylindrical forward extension, a front buffer ring having a bore provided with a forwardly facing annular rear end wall, a chuck housing secured to said cylinder and a rotatable chuck sleeve mounted in said chuck housing and projecting rearwardly into said cylinder, the improvement consisting of a replaceable sleeve-like wear bushing fitted in the bore of said front buffer ring with its rear end in abutting engagement with said annular rear end wall for guiding said piston extension, said bushing having a reduced forward portion providing a forwardly facing shoulder and removable forwardly from said buffer ring bore, and a replaceable cylinder wear bushing arranged coaxially with said sleeve-like bushing and in which the rearward portion of said chuck sleeve is received and rotatably mounted, said cylinder bushing arranged at the forward side of said buffer ring bushing and having an inwardly directed rear annular flange surrounding said reduced forward portion of said buffer ring bushing and the rear surface of said flange abutting said shoulder to hold said buffer ring bushing against forward axial displacement from the bore of said buffer ring. JOHN C. CURTIS.

EIMER G. GARTIN.

(References on following page) menager REFERENCES CITED The following references lare of record inl the le of this patent:

UNITED STATES PATENTS 5 Number Name Y Date 1,443,128 Hansen Jan. 23,1923 1,504,513 Ruffner Aug. 12, 1924 1,564,793 Hulshzer Dec. 8, 1925 1,594,922 Bayles Aug. 3, 1926 10 Number N umher I 155,475

8 Name Date Smickle. Feb. 1, 1927 Penberthy May 24, 1927 Olander June 9. 1931 Gartin June 1, 1937 FOREIGN PATENTS I Country Date Great Britain Jan. 3, 1921 

